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TMS570LC4357: CAN example issue

Jim Meyer
Intellectual 400 points

Part Number: TMS570LC4357

Tool/software:

I am building examples for the TMS570LC43x LaunchXL2.5 development board.  I’ve set up a simple example to transmit CAN messages but I don’t seem to be able to observe any activity on the bus.  I’ve tried DCAN1 and DCAN2 with no success.  I’ve connected the CAN TX/RX lines to and external Analog Devices transceiver – EVAL-ADM3054EBZ.

The registers appear to be set up correctly and a transmit request is set (the correct data is loaded into the data registers).  No observable activity on TX/RX lines. 

I’m using canInit() followed by canTransmit() followed by a 2 second delay (in a loop).

We have the "TMS570LS12x" development board, as well, and we're not seeing this issue.  

  • 0
    TI__Guru* 76876 points

    Hi Jim,

    Jim Meyer said:
    We have the "TMS570LS12x" development board, as well, and we're not seeing this issue.  

    This board have onboard CAN transceivers (SN65HVDA541) right?

    I think here you didn't use external Analog Devices transceiver – EVAL-ADM3054EBZ.

    I want you to make sure the following things first:

    1. Make sure to connect two power supplies.

    2. Not only Tx and Rx lines of CAN but also make sure to connect the launchpad ground to the below highlighted GND1 of external transceiver.

    3. And don't connect 5V to the VDD1 and only use 3.3v

    This is because if you connect 5v on the input then minimum voltage to detect logic high will be 3.5 (0.7*5V) as per the ADM3054 datasheet

    But if you verify logic high level voltage from TMS570LC4357, it can't be more than 3.3v as we typically connect 3.3v to the VCCIO.

    So that means 3.3V logic high from the controller may not be detected as logic high by the CAN controller.

    So please make sure these things and let me know.

    --
    Thanks & Regards,
    Jagadish.

  • +1 in reply to jagadish gundavarapu
    Intellectual 400 points

    Jagadish,

    Great!

    The TMS570LC43x LaunchXL2.5 development board actually doesn't have the onboard CAN transceivers.  However, when I made the connections you suggested, I got CAN output!  Thanks!